This invention relates to an apparatus for servicing cooling systems of the type utilizing a compressible refrigerant as the cooling medium. More particularly, this invention relates to an apparatus for the reclamation and charging of refrigerants from and to a cooling system wherein the refrigerant is precluded from escape to the atmosphere.
It is well known that the dumping of presently used refrigerants which consist of chlorofluorocarbons (CFC) is extremely damaging to the environment due to their deleterious effect on the ozone layer. Moreover, there is now worldwide agreement on regulating production and use of CFC's. As a result, the cost of CFC's, which is already high, will rise dramatically.
Presently, there is no easy, practical method for evacuating a charged refrigeration system of its refrigerant (CFC) and storing it in a receiver. This is primarily because of the nature of the refrigerant. Most refrigerants, (such as FREON) exist as a gas at room temperature and atmospheric pressure. Within a pressurized refrigeration system at room temperature, the freon exists as both a liquid and a gas. If a direct connection were made from the refrigeration system to a receiver, the freon gas would expand and the freon liquid would boil until enough gas would enter the receiver to equalize the pressure in the receiver and the refrigeration system. The net result would be that only a small amount of freon would be transferred into the receiver.
If a pump were used to pump the freon from the refrigeration system to a receiver it would have to be designed to pump both liquid and gaseous freon at the same time. This would make the pump both expensive and bulky. A vacuum pump cannot be used to transfer the freon since the freon would build up pressure as it enters the receiver, and a vacuum pump cannot discharge into a pressurized system.
Finally, heating the freon in the refrigeration system until it all boils off and transfers to the receiver is possible but not very practical. This is because the bulk, shape, and installation of most refrigeration systems does not easily lend itself to being heated. Also, overheating the system could cause excessively high pressure and could therefore be dangerous.
Prior art devices have been suggested for the recovery and charging of refrigerants. U.S. Pat. No. 4,539,817 uses a standard refrigeration system which cools the recovered freon indirectly by utilizing an evaporator coil in a sealed tank. The coolant in the evaporator coils (auxiliary refrigerant) is cooled by the unit's standard refrigeration system. This creates a temperature difference between the auxiliary freon in the coils and the freon in the tank (e.g. the freon to be recovered). As a result, the freon in the tank is cooled, creating a pressure differential, and allowing freon to flow into the recovery tank.
U.S. Pat. No. 4,646,527 describes a refrigerant recovery system which utilizes a pair of accumulators connected in line between a compressor and the refrigeration system to be evacuated. U.S. Pat. No. 4,476,688 discloses a self-contained refrigerant recovery system which involves diverting a portion of liquified gas to an evaporator coil which is in heat exchange relationship with a condenser coil. U.S. Pat. No. 3,232,070 utilizes a compressor or pump to remove refrigerant and deliver it to a receiver. Finally, U.S. Pat. Nos. 4,554,792; 4,480,446; 4,441,330; 4,364,236; 4,363,222; and 4,261,178 all relate to use of a pump (e.g. vacuum pump) to evacuate refrigerant from a refrigeration system.
Despite the large number of proposed refrigerant recovery and charging devices, there continues to be a need for an apparatus which is simple in design and therefore less expensive to manufacture. There is also a need for a refrigerant recovery device which has the ability to fully evacuate the refrigerant from a given system; and if possible, to utilize existing standard refrigeration receivers for recovering the refrigerant.